The invention relates to a surgical retractor, particularly for the spreading of a parted sternum, with a holding device and two spreader arms, said spreader arms being held with one end on the holding device at a spacing from one another that is adjustable in a spreading plane. One or more retaining elements are arranged on each of the spreader arms for the retention of bone material, for example the parted sternum.
Surgical retractors of the aforementioned type are used, in particular, for operations on the heart in order to gain suitable access. The sternum is parted centrally in the longitudinal direction thereof and the sternum halves are forced back to either side, i.e. retracted, together with the adjacent ribs, by means of the retractor.
As a result of the shape and arrangement of the ribs, the observed stiffness at the cranial end of the sternum halves is significantly greater than at the caudal end.
As a result of the varying stiffness, with conventional retractors in particular, in which the achieved opening widths of the sternum are the same in the cranial and caudal directions, in the absence of any additional setting or adjusting capability, unfavourable forces arise along the vertical axis of the sternum.
Particularly in the case of the cranially positioned ribs, due to the substantially greater stiffness there, larger forces occur than at the caudally positioned ribs. This, in turn, results in increased stresses in these ribs, as a result of which greater postoperative pain can occur.
The pain results, above all, if a cranially positioned rib damages the brachial plexus (Plexus brachialis) which is positioned in the region of the shoulder, due to the deformation of said rib or even splintering of pieces off the rib in this region.
In an extreme case, the breakage of a cranially positioned rib can even occur. Since these ribs are positioned under the clavicle, rib breakages are not detected in a normal X-ray image. However, recent studies show that they occur more often than previously suspected.
From US 2007/0161865 A1, there is known a surgical retractor in which this problem is partially taken into account in that the holding device is configured slightly bow-shaped so that the retaining elements arranged at the free ends of the spreader arms perform a slightly bow-shaped movement during retraction. A further adaptation is enabled by a spreader arm which is held on the holding device pivotable in the spreading plane. However, the latter requires additional intervention and adjustment, making the process more complex and more time-consuming.
It is an object of the present invention further to develop the retractor mentioned in the introduction for sternotomy such that a gentler opening of the parted sternum is made possible.